The field of the disclosure relates generally to artificial gas lift systems, and more particularly, to gas lift valve assemblies and methods of assembling gas lift valve assemblies.
Artificial gas lift systems are often used to facilitate the extraction of fluids, such as hydrocarbons, from subterranean fluid-containing formations having insufficient pressure to naturally force fluids out of the formation through a wellbore. Such gas lift systems generally include a well casing lining the wellbore, and a production tubing extending into the fluid-containing formation. Pressurized fluid is injected into the production tubing through an annulus defined between the production tubing and the well casing. The pressurized fluid enters the production tubing through one or more gas lift valve assemblies disposed at various depths along the production tubing. The pressurized fluid displaces denser production fluids within the production tubing, thereby decreasing the hydrostatic pressure within the production tubing and enhancing the rate at which fluids can be extracted from the subterranean formation.
Industry standards for acceptable leak rates through gas lift valve assemblies used in artificial gas lift systems have become increasingly stringent in recent years, particularly for off-shore and deep sea gas lift systems. Meeting such industry standards using known gas lift valve assemblies has presented significant challenges due in part to the wide range of pressures and temperatures experienced within the production tubing during operation.
Some known gas lift valve assemblies utilize a check valve to inhibit fluid within the production tubing from leaking to the annulus. The sealing components of such gas lift valve assemblies, however, are typically located directly in the path of fluid flow. As a result, the sealing surfaces of the sealing components are exposed to high velocity fluid flow, which may contain solid, abrasive particles, causing rapid wear of the sealing components.
Accessing gas lift valve assemblies within the gas lift system for maintenance or repairs is generally difficult, costly, and requires a significant amount of down time for the gas lift system. Such down time can result in a significant amount of production losses. In some instances, for example, accessing a gas lift valve assembly for maintenance or repairs can require one to two days of down time, and can have a total cost in excess of $1 million. Accordingly, a continuing need exists for a gas lift valve assembly having an acceptable leak rate and an improved service life.